Youth in military-connected families may be exposed to potentially deleterious stressors associated with family member deployment and/or family relocations. These stressors have been found to be associated with externalizing behaviors such as substance use and suicidality. We know that an optimal measurement of stress and stressful life events should include items that are behaviorally-specific, i.e., tailored to the concerns of the target population. Leading measures of adolescent stress do not assess the unique stressors of military connected youth - such as multiple moves, or worrying about a family member who is or may soon be deployed or given a dangerous assignment. Thus, the present study seeks to develop a military related measure of adolescent stress. The aims are to: 1) develop the Adolescent Military Stress Measure (AMSM) to assess level of stress across the deployment cycle (i.e., pre- deployment, deployment, and reintegration), and during transitions and relocations, 2) obtain test-retest reliability and validity assessments of the AMSM developed in Aim 1 via sub-aims 2a) conduct known groups validity assessment by comparing overall and specific types of stress experienced by military-connected youth compared to non- military connected youth and 2b) assess the association between responses to the AMSM and youth substance use, suicidality, and the Adolescent Stress Questionnaire as indicators of predictive and concurrent validity. There are nearly 1.2 million school-aged military-connected children. Few studies have attempted to describe how youth experience the different stressors within deployment cycles in the context of psychosocial transitions. Specifically, there is a dearth of empirical data on the impact of the unique interplay or combined impact of relocations and deployments on adolescent behavioral health. Therefore, there is a need for an empirically-reliable measurement tool to capture the experiences and impact of military- related stress among adolescents.